The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Hybrid vehicles having an internal combustion engine as a first source of motive power and an electric motor as a second source of motive power have become increasingly popular based on fuel costs and environmental concerns. In at least one hybrid vehicle, it may be beneficial to frequently start and stop the operation of the internal combustion engine to most efficiently operate the vehicle. To minimize and/or eliminate the noise, vibration and harshness associated with typical internal combustion engine starting systems, it may be desirable to position a starter motor gear in constant meshed engagement with a member of the internal combustion engine. To allow temporary driving interconnection between the starter motor and the internal combustion engine, it may be desirable to position a clutch along this power path.
While various clutch designs may be incorporated, specific cost, size, weight and torque carrying capacity concerns exist.
Traditional overrunning clutches may include an inner race having a smooth outer surface, an outer race having a cam profiled inner surface and rollers positioned between the inner race and the outer race. Each roller is held in position with a corresponding spring to allow the clutch to operate in a locked or an unlocked mode depending on relative rotation between the inner race and the outer race. Manufacturing tolerances of the various clutch components have typically combined to allow less than every clutch roller to simultaneously contact inner and outer races. Accordingly, the maximum torque transferred by the clutch is less than a torque magnitude that could be transferred if each roller were simultaneously sandwiched by the inner and outer races.
Furthermore, known overrunning clutches often lack concentricity between the inner race and the outer race when the clutch operates in the overrunning mode. This condition exists because the rollers are no longer in driving contact with both the inner and outer races and relative movement between the races is allowed. Depending on the components coupled to the inner and outer races, this lack of concentricity may provide undesirable results such as improper gear meshing, shaft support and the like. Based on the above-mentioned concerns, it may be desirable to provide an improved sealed high capacity overrunning roller clutch.